Self-adjusting contra rotating axial flow pumps and turbines



y 1963 c. OZGUR 3,088,414

SELF-ADJUSTING CONTRA ROTATING AXIAL FLOW PUMPS AND TURBINES Filed001',- 7, 1960 INVENTOR.

CAH IT 0 ZGUR v United States Patent 3,088,414 SELF-ADJUSTING CONTRAROTATING AXIAL FLOW PUMPS AND TURBINES Cahit Ozgur, Lachine, Quebec,Canada, assignor to Dominion Engineering Works Limited Filed Oct. 7,1960, Ser. No. 61,200

3 Claims. (Cl. 103-94) This invention relates to new and improvedhydraulic pump-turbines of the axial flow type and has particularreference to the provision of new and improved means for 1mproving theperformance thereof and extending their useful range 'of operation byautomatically eliminatmg the whirl component'of the velocity at theoutlet of the runner.

In the past attempts have been made to reduce or correct the whirl atthe outlet by employing fixed or adjustable guide vanes and separatelydriven contrarot-ating runners have been employed.

Where the fixed or adjustable guide vanes were used, it has been foundthat the correction of the whirl was made at the expense of additionalfriction losses. Also there was lack of adaptability and worsening ofthe per formance for reverse flow operation in regard to efficiency andalso danger of cavitation and there also was lack of flexibility forcertain operating conditions where fixed guide vanes were employed.

Where separately driven'contra-rotating runners were employed, the lackof adaptability and worsening of performance for reverse flow operationand danger of cavitation as well as the fact that the correction of thewhirl was made at the expense of additional friction losses but to alesser degree but this variable speed arrangement of the separatelydriven contra-rotating runners led to complicated and expensive design.

It is the object of the present invention to provide new and improvedmeans for improving the performance of axial flow pump-turbines toextend their useful range of operation by eliminating automatically thewhirl component of the velocity at the outlet of the runner, whicharrangement is relatively simple and economical in construction yetefiicient in operation.

Referring to the drawings:

FIGURE 1 is a schematic view, partly in section, of a device embodyingthe invention;

FIGURE 2 is a fragmentary view of the device shown in FIGURE 1 on anenlarged scale; and

FIGURE 3 is a schematic end view of the planetary gear system.

Referring more particularly to the drawings wherein similar referencecharacters designate corresponding parts throughout, the device showncomprises two coaxial runners A and B which are driven by a fixed speedshaft S through a planetary gear system, designated generally as P, andwhich gear system is so chosen that it distributes the power that underall established operating conditions the mechanical torque applied torunner A is equal and in the opposite direction to that applied torunner B.

According to the basic law of turbo-machinery, hydraulic torque-sdeveloped by the two runners can only be equalized when the whirlsimparted to the water by the runners are equal and in the oppositedirection. In other words, in the case of straight inflow to runner A,equilibrium of the hydraulic torques is only possible when the whirlgiven to the water by runner A is taken out by runner B.

Since the mechanical torques delivered to the runners need always to beequal to the hydraulic torques developed, it leads to the conclusionthat under all operating conditions, discharge and head, the two runnerswill take automatically the right speed to provide straight outlet flowfrom the machine when the inlet flow is straight.

Similarly, if the flow has an initial at the inlet of the machine, atthe outlet. G and G are supporting ribs which carry the bearings of therunners. In the case that it is desirable to have an outlet flow with aslight whirlcomponent, the upstream ribs can be set at the necessaryangle. Since the flow will have the same whirl at the outlet of thesecond runner the downstream ribs must be set at the same angle.

From the foregoing it will be seen that the pump will operate in thesame manner when the flow is reversed provided that the shaft S isdriven in the reverse direc-v tion.

When the device is running as a turbine, shaft S will be driven throughthe two runners, through the planetary gear system P and water goinginto the turbine with axial velocity will leave the second runnerwithout having a whirl component.

The form of planetary system shown which is capable of transferringalways equal and opposite torque to each of the runners and alsosuitable for a contra-rotating double coaxial runner arrangementcomprises a gear 1 directly fastened to the main shaft S and rotates atthe same speed n. Gear 4 is fastened to the stationary shaft F carriedby support ribs 6;.

Disc 0 carrying the planet gears 2 and 3 rotates idly about the mainaxis with a speed n and its short central shaft 7 is guided andsupported by shafts F and S.

On the periphery of disc 0 are mounted several small shafts 8 on whichplanet gears 2' and 3 rotate idly. A plurality of such shafts 8 and setsof gears 2 and 3 are provided, preferably 3. The internal ring gears 5and 6 are fixed inside the runner hubs and the speeds of these gears areshown as n and n Positive direction for runner B being opposite to thatof the main shaft.

A simple analysis of the above system leads to the following speedrelation:

whirl component It will come out unaltered where D is the diameter ofgears 5 and 6 and d that of the gears 1 and 4.

Note that in the case of D=2d, the speed of driving shaft S is fourtimes greater than the main speed of runner-s A and B.

It will be seen that the present device comprises basically a hydraulicpump-turbine having two coaxial propellertype wheels of opposite handwith two fixed spiders attached to the wall of the throat with the shafthaving a first simple planetary gear train attached thereto andcomprising a sun gear attached to the shaft and a plurality of planetpinions operably mounted on a free spider and a ring gear attached tothe first of the wheels, which wheel is journalled on the hub on thefirst of the fixed spiders and which shaft is also journalled in the hubof said first fixed spider and a second simple planetary gear trainhaving substantially the same gear ratio as the first planetary geartrain and comprises a sun gear fixed to the second of the fixed spidersand a plurality of planet pinions operably mounted on the free spiderand a ring gear attached to the second of the wheels which wheel isjournalled on the hub of the second of the fixed spiders.

It will be seen that with the present invention straight outlet flow isobtained for all operating conditions whereby efiiciency is improved fora very large range of operations and instability caused by swirling flowis eliminated, Also, in the case of relatively long discharge pipes,friction losses in pipes are reduced for pumps and there will be, inturbine operation, no radial pressure gradient to cause additionalcavitation problem.

Furthermore, peak efiiciency of the unit is believed to be higher thanpumps having one runner and one outlet straightening vain system due tothe fact that in the latter, recoveries are made through thestraightening vanes at the expense of extra losses while in the presentinvention no recovery of the whirl component is necessary.

It will also be seen that the present invention, for pump operation thehead is split between the two runners and thus, cavitation conditionsare improved and the need for an additional governing system iseliminated.

Furthermore, the driving system employed is simpler than that of theseparate driven contra-rotating arrangement and versatility of thesystem can be so arranged as to provide the desirable speed ratiobetween the runners and the driving shaft.

The system is suitable for turbines, pumps, pump turbines and in bothdirect and reverse operation.

It will be seen that the arrangement can be modified to meet particularrequirements such as, if it is desired to give the water a slight Whirlthrough the two runners, the planetary system can be chosen to supply aslightly different torque by giving gears 1 and 4 different diametersand making corresponding changes to the two planet gears. Also runnersmay have either variable or fixed blades and can either be builtidentical or to different design according to the requirements.

From the foregoing it will be seen that I have provided new and improvedmeans for obtaining all of the objects and advantages of the invention.

I claim:

1. A hydraulic pump-turbine having two coaxial propeller-type wheels ofopposite hand, a shaft, spider means for supporting said wheels inoperable position and means connecting said wheels for powertransmission to said shaft and to each other and to said spider means,said connecting means comprising two simple planetary gear trainsemploying a common free planet carrier.

2. A hydraulic pump-turbine having two coaxial propeller-type wheels ofopposite hand, a shaft, spider means for supporting said wheels inoperable position and means connecting said wheels for powertransmission to said shaft and to each other and to said spider means,said connecting means including a pair of inter-connected planetary gearmeans such that the torques imparted to said wheels are equal.

3. A hydraulic pump-turbine having a throat and two coaxialpropeller-type wheels of opposite hand, two fixed spiders attached tothe wall of the throat, a shaft, a first simple planetary gear traincomprising a sun gear attached to said shaft, a plurality of planetpinions operably mounted on a free spider and a ring gear attached tothe first of said wheels which Wheel is journalled on the hub on'thefirst of said fixed spiders and said shaft is also journalled in the hubof said first fixed spider, a second simple planetary gear train havingsubstantially the same gear ratio as the first planetary gear train andcomprising a sun gear fixed to the second of said first spiders, aplurality of planet pinions operably mounted on said free spider and aring gear attached to the second of said wheels which wheel isjournalled on the hub of the second of said fixed spiders.

References Cited in the file of this patent UNITED STATES PATENTS1,547,467 Swanson July 28, 1925 2,560,216 Coponat -a July 10, 19512,561,090 Baumann July 17, 1951 2,584,555 Cleave et a1. Feb. 5, 19522,689,681 Sabatiuk Sept. 21, 1954 2,955,747 Schwaar Oct. 11, 19603,038,307 Oprecht June 12, 1962 FOREIGN PATENTS 58,032 Netherlands Aug.15, 1946 214,761 Germany Feb. 23, 1956 399,619 Great Britain Oct. 12,1933 815,268 France Apr. 5, 1937 947,189 Germany Aug. 9, 1956 963,415-France Jan. 4, 1950

1. A HYDRAULIC PUMP-TURBINE HAVING TWO COAXIAL PROPELLER-TYPE OFOPPOSITE HAND, A SHAFT, SPIDER MEANS FOR SUPPORTING SAID WHEELS INOPERABLE POSITION AND MEANS CONNECTING SAID WHEELS IN OPERABLE POSITIONAND MEANS SHAFT AND TO EACH OTHER AND TO SAID SPIDER MEANS, SAIDCONNECTING MEANS COMPRISING TWO SIMPLE PLANETARY GEAR TRAINS EMPLOYING ACOMMON FREE PLANET CARRIER.